The U.S. Senate on Friday struggled to pass a $1.1 trillion spending bill that would avert a looming federal government shutdown, postponing a vote until Monday when procedural hurdles begin to evaporate.

Negotiations between Democrats and Republicans to speed the process along collapsed during late-night talks in the nearly abandoned U.S. Capitol.

Barring any agreement to act in a more streamlined way, the Senate is on track to hold a procedural vote at 1 a.m. eastern time Sunday aimed at clearing the way for passage on Monday.

The breakdown in talks capped a week in which passage of the massive spending bill to fund most of the government through Sept. 30, 2015, advanced in fits and starts.

Some senators, angered over the bill’s easing of a “Dodd-Frank” bank regulation law requirement, wanted a shot at removing the provision.

But demands from some conservative Republicans for a separate vote on an amendment to immediately defund President Barack Obama’s implementation of a recently announced immigration program further stymied the bill’s progress on Friday.

In order to keep federal agencies operating beyond midnight Saturday, when existing funds expire, the Senate is expected to pass sometime Saturday a stop-gap bill to temporarily fund the government through the middle of next week.

The House of Representatives already passed such a measure anticipating the Senate’s inability to finish the broad spending bill this week.

The 1,603-page spending bill, negotiated by Republican and Democratic appropriators and leaders, narrowly passed the House on Thursday following a battle that exposed fraying unity in Obama’s Democratic Party.

A revolt over financial provisions by House Democratic leader Nancy Pelosi, long a staunch Obama ally, led to a day of tension on Capitol Hill on Thursday.

Democrats balked at rolling back part of Dodd-Frank, an early legislative achievement of the Obama administration that was passed in response to the 2008 financial crisis and aimed to rein in risk-taking by Wall Street. Democrats also objected to a provision allowing bigger political donations.

The Dodd-Frank provision would kill planned restrictions on derivatives trading by large banks, allowing them to continue trading swaps and futures in units that benefit from federal deposit insurance and Federal Reserve loans.

Democrats, aware of the need for unity when Republicans take full control of Congress next year after their midterm election gains, tried to tamp down speculation of a lasting split between Obama and Pelosi. One leadership aide said Pelosi had fired a warning shot to Republicans that House Democrats would fight hard in the new year.

Reid opened Friday’s debate on the bill urging quick passage. “Since 2011 we have lurched from crisis to crisis with the country constantly under the threat of shutdown or financial catastrophe,” he said.

McConnell was also anxious to avoid another unpopular government shutdown as the Republicans head toward taking control of the Senate after the November elections that also gave them a larger House majority.

PLAYING DOWN THE DIVIDE

Democrats seeking to play down the Pelosi-Obama divide noted that the two actually were in agreement that the Dodd-Frank measure and some other Republican add-ons were objectionable, but differed on stopping the bill because of them.

While Pelosi put up a spirited fight to kill the add-ons, she stopped short of trying to slay the spending bill late Thursday by demanding “no” votes by her Democrats.

The battle was a warning to Republicans against further erosion of Dodd-Frank or the president’s landmark healthcare law, said a House Democratic leadership aide.

If such challenges arise next year, Pelosi said, “Should the president threaten a veto, the votes will be here in the House to sustain it.”

Democratic fervor against the Dodd-Frank provision was stirred up in part by Senator Elizabeth Warren, viewed as a possible 2016 presidential candidate.

In a Senate floor speech Friday, she singled out Citigroup’s “influence” on the U.S. political process.

“Let me say this to anyone who is listening at Citi: I agree with you. Dodd-Frank isn’t perfect. It should have broken you into pieces.”

In the 219-206 House vote, 67 Republicans rejected the spending bill, largely because it failed to take action to stop Obama’s immigration order. But that was offset by 57 Democrats who voted in favor.

The spending bill would fund all government agencies through September 2015, except for the Department of Homeland Security, which would get an extension only through Feb. 27. That is the department mainly in charge of implementing the order announced by Obama last month.

(Reporting by Richard Cowan and David Lawder; Additional reporting by Susan Cornwell and Amanda Becker)